JP2011509431A - Toner roller with an insulating layer containing plastic - Google Patents

Abstract

  The toner roller includes a roller-shaped base body (12). An insulating layer (14) is disposed on the base body (12), and the insulating layer (14) contains plastic. Preferably, the insulating layer contains, in addition to plastic, fillers such as conductive carbon black and oxide ceramic.

Description

  The present invention is a toner roller for use in a developing station of a printer or a copier, and includes a roller-shaped substrate, the substrate has a conductive surface, and an insulating layer is disposed on the surface. Related to what is being. The invention further relates to a method of manufacturing a toner roller.

  The toner roller is an important component in the development station of a printer or copier. A typical toner roller is used as an applicator roller, which is opposed to an intermediate carrier, such as a photosensitive drum or photosensitive belt. The applicator roller supports a homogeneous layer of toner particles during operation. The surface of the intermediate carrier is provided with a latent charge image corresponding to the image to be printed. Based on the force of the electric field, the toner particles are attracted from the surface of the intermediate carrier, and possibly are transported from the applicator roller to the surface of the intermediate carrier over the air gap, and are arranged according to the charge latent image.

  The roller-shaped substrate has a conductive surface, whereby the toner particles can be held on the surface of the toner particles using a voltage. In order to prevent a flashover from occurring towards the intermediate carrier inside the development station, the toner roller must be provided with an insulating layer. The insulating layer must have sufficient abrasion resistance to the developer mixture containing toner particles and ferromagnetic carrier particles.

  In US Pat. No. 6,327,452 and US Pat. No. 5,473,418, a toner roller is known, and the toner roller uses a ceramic layer as an insulating layer. This ceramic layer is provided with a pore capable of absorbing moisture, thereby suppressing the function of the toner roller in particular for receiving and delivering toner particles.

  The object of the present invention is to improve the toner roller and the method of manufacturing the toner roller so that the surface of the toner roller is suitable for supporting the toner layer, has high voltage resistance and wear resistance. Is to provide.

  This problem is solved by a toner roller having the configuration described in the characterizing portion of claim 1. Advantageous refinements are described in the dependent claims.

  According to the invention, the insulating layer contains plastic and has a layer thickness in the range of 150 μm to 1000 μm. The insulating layer is configured as a cylinder sleeve and contacts the surface of the substrate.

According to a preferred embodiment, the insulating layer contains a filler in addition to the plastic, and the insulating layer provides a predetermined electrical resistance, a predetermined high voltage resistance, and a predetermined wear resistance. . As the plastic material, especially urethane (e.g. PU polyurethane) or fluorocarbon material (polyfluorocarbon, for example PTFE (Teflon ^(R)), ECTFE, ETFE, PVDF, PFE) are a group of possible. Plastics from the urethane group are characterized by isocyanate groups or NCO groups, and plastics from the polyfluorocarbon group are characterized by substitution of CH ₂ groups by fluorine atoms. Both plastic groups are characterized by the ability to mix large amounts of fillers. Furthermore, both plastic groups have exceptional wear resistance based on the polymer structure. In order to adjust the electrical resistance, conductive additives are used, preferably conductive carbon black or nanoparticles, such as carbon nanotubes. As fillers to be mixed into the plastic, in particular non-plastic materials such as SiO ₂ , carbon, ceramic oxide, aluminum oxide, titanium oxide and / or chromium oxide and mixtures thereof are conceivable.

  From another aspect of the present invention, a toner roller manufacturing method has been described.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 4 is a transverse sectional view and a longitudinal sectional view of a toner roller. FIG. 7 is a diagram illustrating a usage state of a toner roller in a developing station. It is a figure which shows the state of the electric potential in a developing station.

In FIG. 1, the toner roller 10 is shown in a cross-sectional view on the upper side and in a vertical cross-sectional view on the lower side. The toner roller 10 includes a roller-shaped base 12 and an insulating layer 14. The insulating layer 14 has a layer thickness in the range of 150 μm to 1000 μm, preferably 400 μm to 600 μm. In this embodiment, the base 12 can be formed as an internal roller provided with a bearing journal 16. A hollow roller may be used as the substrate 12. The roller-like substrate 12 is preferably made of aluminum or an aluminum alloy (including aluminum-forging alloys, aluminum-casting alloys and aluminum-die casting alloys), or pure titanium or titanium alloys. ing. Optionally, the substrate can be made from plastic, the substrate comprising a conductive surface. The conductive surface of the substrate 12 is important. This is because a DC voltage is applied to the conductive surface, and the toner particles are attracted to the outer surface of the insulating layer 14 based on the electric field force. The specific resistance of the conductive material on the substrate 12 or the conductive surface of the substrate 12 is smaller than 10.0 Ω · mm ² / m. A layer having an antistatic effect is provided, whereby a surface charge generated in some cases can be derived (relative value (specific resistance of layer material): 10 ⁶ Ohm cm <layer <10 ¹⁴ Ohm cm Value (absolute resistance of the layer) <10 ⁸ Ohm). The layer thickness is defined from such a requirement. The resulting attenuation of the DC electric field applied to the substrate relative to the roller surface must be at most 80%. The capacitance of the layer structure must be between 100 pF (piko-Farad) to 1 μF (Mikro-Farad) in order to obtain a small capacitive resistance. Ideally, the dielectric constant of the layer is greater than 7. As the electrical value of the layer, a frequency range of 0 Hz to 1 Hz applies for sinusoidal vibration.

  FIG. 2 shows the usage state of the toner roller 10 in the developing station 20. The developer mixture 22 containing toner particles and ferromagnetic carrier particles is conveyed to the inking roller 26 by the mixture takeout member 24. The inking roller 26 includes a magnet element 28 as a magnet stator, and the magnet element 28 attracts carrier particles having magnetism. When the sleeve of the inking roller 26 rotates, the carrier particles are further conveyed upward together with the toner particles adhering to the sleeve. At the contact portion 30 between the inking roller 26 and the toner roller 10, the toner particles and the carrier particles are separated. The toner particles are held on the insulating layer 14 of the toner roller 10 based on the force of the electric field and conveyed upward, whereas the ferromagnetic carrier particles are transferred to the developer mixture 22 in the direction of the arrow P1. Or returned toward the cleaning roller 34.

  The toner particles adhering to the surface of the toner roller are guided beside the photosensitive layer of the intermediate carrier 32, for example, a belt-shaped photoreceptor, and are based on a latent charge image between the photosensitive layer of the intermediate carrier 32 and the surface of the toner roller 10. By the force of the electric field formed in this way, it flies to the photosensitive layer and colors the image. The toner roller 10 that is used by the flying operation of the toner particles at the contact portion between the toner roller 10 and the intermediate carrier 32 is often called a jump roller (Jump-Walze). Untransferred toner particles are removed from a cleaning roller 34 having a magnet stator having a magnet element 35 using ferromagnetic carrier particles. The toner particles and carrier particles to be removed are supplied again to the developer mixture 22 in the direction of the arrow P2.

  FIG. 3 illustrates the state of the potential in the developing station 20. The charging roller 26 is applied with a DC voltage potential, while the toner roller 10 is applied with an AC voltage that can be superimposed on the DC voltage. The cleaning roller 34 is applied with a potential opposite to that of the inking roller 26. The potential applied is selected such that the toner particles can be transported upwardly from the developer mixture 22 toward the intermediate carrier 32 on the one hand and separated from the toner roller 10 on the other hand. Can fly to the photosensitive layer.

  The contact portion between the inking roller 26 and the toner roller 10 and between the toner roller 10 and the cleaning roller 34 passes through this gap due to a relatively narrow gap (typically 1.0 mm). High mechanical loads on the roller surface occur due to the hard ferromagnetic carrier particles being conveyed. Therefore, the insulating layer 14 on the toner roller 10 needs to have wear resistance, and thus wear is small and a long service life of the toner roller 10 can be obtained. Furthermore, the insulating layer 14 needs to be formed so as not to cause a short circuit between the individual rollers based on the applied high voltage. Therefore, the toner roller 10 requires an insulating layer, whereas the inking roller 26 and the cleaning roller 34 can be provided with a conductive layer. In the positive half wave of the AC voltage applied to the toner roller 10, the potential difference with respect to the cleaning roller 34 is about 2 kVss, and in the negative half wave, it is 3 kVss or less. Therefore, high quality operation can only be realized if sufficient high voltage tolerance is provided by the insulating layer 14 of the toner roller 10. On the one hand, it is difficult to find a suitable material for the insulating layer 14 due to the demand for high wear resistance and on the other hand the demand for high high voltage resistance. The thickness of the insulating layer 14 is typically 150 μm to 1000 μm. In layers that are too thin, flashover due to high voltages can occur. Even thinner layers present problems with regard to wear resistance. If the insulating layer is too thick, the electrical insulating effect is too great.

  Hereinafter, examples of the insulating layer 14 will be described.

Example 1
The insulating layer is made of a filler in addition to the plastic. A conductive additive, particularly conductive carbon black, is supplied to the filler. Nickel as a filler - plastic, such as SiO _2, carbon, aluminum oxide, is considered titanium oxide and / or chromium oxide. The content of the filler contained in the insulating layer is 0 to 15 mass percent, preferably 3.6 to 15 mass percent. The content of the conductive additive contained in the insulating layer is 0.1 to 0.5 mass percent, preferably 0.2 to 0.28 mass percent.

Example 2
As in Example 1, except PTFE (Teflon ^(R)) is provided as the plastic.

Example 3
As in Example 1, except PVDF as a plastic (e.g. Kynar ^(R), PA (polyamide), PE, PVC, polyolefin or polyurethane (PU) is used.

Example 4
The insulating layer is made of pure, ie unadded polyurethane (PU).

The insulating layers obtained by these examples have the following characteristics.
a) The insulating layer is resistant to abrasion against ferromagnetic carrier particles and iron powder, and has wear resistance.
b) The insulating layer has electrical insulation,
c) The insulating layer has a high voltage tolerance of at least 2 kVss,
d) the specific contact resistance of the insulating layer is at least 10 ⁷ Ωcm;
e) Surface characteristics are hardly affected by the surrounding environment, such as air humidity and temperature,
f) The surface roughness is smaller than 2 μm as the average roughness Rz,
g) The non-circularity of the surface is smaller than 7 μm,
h) The surface is preferably non-adhesive.

  The proposed insulating layer has sufficient high voltage tolerance. This prevents the outer surface from being peeled off and damaged, thereby providing a long service life of the toner roller and thus the development station. The described insulating layer has sufficient wear resistance. By using plastic for the insulating layer, the surface is well sealed, so the surface does not absorb moisture. Moisture absorption can occur on porous formed surfaces. For certain plastics, post-processing such as polishing is omitted.

  In the following, several different manufacturing methods for manufacturing the toner roller will be described.

Manufacturing method 1
In accordance with the previous examples, particulate or powdered plastic is mixed with particulate or powdered filler to form a dispersion or suspension. The substrate is immersed in the dispersion and the substrate is coated with a thin layer of the dispersion. After the layer has dried, the layer is processed by cutting (eg, by polishing) to obtain the required geometric dimensions, required roughness and surface structure.

Manufacturing method 2
A sheet is made from a mixture of plastic and filler. The sheets are welded together at the two ends and attached to the substrate. Thereafter, post-processing is performed to obtain geometric dimensions.

Manufacturing method 3
A shrink tube is made from a mixture of plastic and filler and attached to a substrate. Next, post-processing is performed.

Manufacturing method 4
Using a mixture of plastic and filler, the substrate is coated by a powder coating method (eg, sintered coating (Wirbelsintern), plastic powder molding, injection molding, electrostatic coating). Next, post-processing is performed.

  In the above manufacturing method, pure polyurethane may be used instead of the mixture of plastic and filler.

  Also suitable as the substrate material are composite materials such as glass composite materials (eg glass fiber reinforced plastics) or carbon fiber composite materials (eg carbon fiber reinforced plastics). In such composite materials, the plastic content is below 50%. Similarly, ceramic or glass is used as the material, for example in the form of a tube. These materials have a conductive layer on the surface. When a conductive carbon fiber, for example, a wound carbon fiber tube, is used for the substrate, a specially attached conductive layer can be omitted when the carbon fiber tube has sufficient conductivity.

  10 toner roller, 12 substrate, 14 insulating layer, 16 bearing journal, 20 developing station, 22 developer mixture, 24 mixture takeout member, 26 fleshing roller, 28 magnet element, 30 contact portion, P1, P2 direction arrow, 32 middle Carrier, 34 Cleaning roller, 35 Magnet element

Claims (17)

A toner roller for use in a developing station of a printer or copier,
A roller-like substrate (12), the substrate (12) has a conductive surface, and an insulating layer (14) is disposed on the surface;
The toner roller, wherein the insulating layer (14) contains a plastic and has a layer thickness in the range of 150 μm to 1000 μm.   The toner roller according to claim 1, wherein the insulating layer includes a filler in addition to the plastic.   The toner roller according to claim 2, wherein the filler contains a conductive additive, particularly conductive carbon black or nanoparticles. The toner roller according to claim 3, wherein the filler contains SiO ₂ , carbon, ceramic oxide, aluminum oxide, titanium oxide and / or chromium oxide.   The toner roller according to any one of claims 2 to 4, wherein the content of the filler contained in the insulating layer (14) is 0 to 15 mass percent.   The content of the conductive additive contained in the insulating layer (14) is in the range of 0.1 weight percent to 0.5 weight percent, preferably 0.2 weight percent to 0.28 weight percent. The toner roller according to any one of 1 to 5.   The toner roller according to claim 1, wherein PTFE is provided as a plastic for the insulating layer.   The toner roller according to claim 1, wherein the insulating layer is made of pure polyurethane.   The toner roller according to claim 1, wherein the insulating layer is attached to the substrate as a shrinkable tube.   The toner roller according to claim 1, wherein the insulating layer is formed by a sheet welded at an end portion.   The roller-shaped substrate is made of aluminum or an aluminum alloy including an aluminum forging alloy, an aluminum casting alloy and an aluminum die casting alloy, or made of pure titanium or a titanium alloy. The toner roller according to any one of 1 to 10.   The substrate (12) comprises a plastic, glass, ceramic or composite material, preferably a glass composite material or a carbon fiber composite material, and the substrate (12) comprises a conductive surface. Item 11. The toner roller according to any one of Items 1 to 10. A method of manufacturing a toner roller for use in a printer or copier development station comprising:
An insulating layer (14) is provided on a roller-shaped substrate (12) having a conductive surface,
The method for producing a toner roller, wherein the insulating layer (14) contains a plastic and has a layer thickness in the range of 150 μm to 1000 μm.   14. A method according to claim 13, wherein the insulating layer (14) is attached to the substrate as a shrink tube.   The method according to claim 13 or 14, wherein the insulating layer (14) is formed by a sheet welded at the ends.   A method according to any one of claims 13 to 15, wherein the insulating layer (14) is formed by an impregnation process with a subsequent drying process.   The method according to any one of claims 13 to 15, wherein the insulating layer (14) is produced by powder coating or injection molding.

Images